U.S. patent number 5,393,513 [Application Number 08/100,664] was granted by the patent office on 1995-02-28 for stable, highly concentrated fluoro carbon emulsions.
This patent grant is currently assigned to Alliance Pharmaceutical Corp.. Invention is credited to David M. Long, Jr..
United States Patent |
5,393,513 |
Long, Jr. |
February 28, 1995 |
**Please see images for:
( Certificate of Correction ) ** |
Stable, highly concentrated fluoro carbon emulsions
Abstract
A non-toxic, brominated perfluorocarbon emulsion for internal
and intravenous use in animals (including humans) is disclosed, for
use as an oxygen transport medium and as a contrast enhancement
medium capable of facilitating the detection of tumors and other
elements within the body. This emulsion is stable and maintains its
very small particle size characteristics for extended periods of
time, often exceeding eighteen months after sterilization, and
further may include a stabilizing component selected from the group
consisting of steroids, tocopherols, cholesterols, and combinations
thereof. An anti-oxidizing component enhances delivery in oxygen
transport.
Inventors: |
Long, Jr.; David M. (El Cajon,
CA) |
Assignee: |
Alliance Pharmaceutical Corp.
(San Diego, CA)
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Family
ID: |
27423129 |
Appl.
No.: |
08/100,664 |
Filed: |
July 30, 1993 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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811026 |
Dec 19, 1991 |
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387947 |
Aug 24, 1989 |
5080885 |
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818690 |
Jan 14, 1986 |
4865836 |
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Current U.S.
Class: |
424/9.37;
436/173; 514/169; 514/171; 514/460; 514/744; 514/757; 514/832;
514/937; 514/941; 514/943; 600/420; 977/904; 977/927 |
Current CPC
Class: |
A61K
9/0026 (20130101); A61K 31/02 (20130101); Y10S
977/904 (20130101); Y10S 977/915 (20130101); Y10S
977/927 (20130101); Y10S 514/937 (20130101); Y10S
514/941 (20130101); Y10S 514/943 (20130101); Y10S
514/832 (20130101); Y10T 436/24 (20150115) |
Current International
Class: |
A61K
9/00 (20060101); A61K 31/02 (20060101); A61K
049/04 (); A61K 031/56 (); A61K 031/35 (); A61B
005/055 () |
Field of
Search: |
;424/5,9 ;128/653.4,654
;436/173 ;514/169,171,460,744,757,937,832,941,943 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Beisbarth, H. and T. Suyama, 5th Intl. Symp. on Perfluorochemical
Blood Substitutes. Mainz: Mar. 1981. .
Persico, D. et al., A General Systhesis for Symmetrical Highly
Branched Perfluoro Ethers J. Org. Chem. 50:5156-5169 (1985). .
Sharts, C. and H. Reese, The Solubility of Oxygen in Aqueous
Flurocarbon Emulsions. J. Fluorine Chemistry 11:637-641 (1978).
.
S. Davis, 2nd International Symposium on Clinical Nutrition
Advances in Clinical Nutrition 19:213-239, Bermuda: May 1982. .
Yokoyama, K. et al., Preparatiion of Perfluorodecalin Emulsion, and
Approach to the Red Cells Substitute, Fed. Proc. 34(6) 1478-1483
(1975). .
Steiner, M. and J. Anastasi, J. Clinical Investigation 57:732-737
(1976). .
Pandolfe, W. D. and R. R. Kinney, "Recent Developments in the
Understanding of Homogenization Parameters" Denver, Colo. Aug. 29,
1983. .
Chandonnet, S. et al., Preparation of Microemulsions by
Microfluidization, Feb. 1985. .
Korstvedt, H. et al., Microfluidization: for Making Fine Emulsions
and Dispersions, Amer. Paint and Coatings Journal, Jan. 28, 1985.
.
Korstvedt, H. et al., Microfluidization, Drug and Cosmetic
Industry, Nov. 1984. .
Allinger, H., Ultrasonic Disruption, American Laboratory, Oct.
1985. .
Berlinger, S. Application of Ultasonic Processors, Biotechnology
Laboratory, Mar. 1984. .
Gould, S. et al., Assessment of a 35% Fluorocarbon Emulsion, The
Journal of Trauma 23(8):720-724 1983. .
Police, A. M. et al., Critical Care Medicine 13(2):96-98 1985.
.
Nunn, G. R. et al., Effect of Fluorocarbon Exchange Tranfusion on
Myocardial Infarction Size in Dogs, American J. of Cardiology
52:203-205 1983. .
Bose, B. et al., Brain Research 328:223-231 1985. .
Spears, J. et al., Circulation (Abstracts) 68 (Supp. III) No. 317
Oct. 1983. .
Patel, M. et al., Survival and Histopathological Changes in Lungs
of Hamsters following Liquid Synthetic Breathing Fed. Proceedings
29(5):1740-1745 1970. .
A Technical Bulletin #67 of the Fauling Corporation Sep. 1982 Peck,
W. W. et al., Investigative Radiology 19:129 1984. .
Gaulin Corp. A Technical Bulletin #67, Sep. 1982. .
Dobben, G. et al., Experimenta Studies with Radiopaque Fluorocarbon
in the Subarchnoid Space, Neuroradiology 6:17-19 1973. .
Brahme, F. et al., Investigative Radiology 11(4):319-330 1976.
.
Long, D. M. et al., Radiology 105(2):323-332 1972. .
Riess, Jean, Artificial Organs 8:34-56 1984..
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Primary Examiner: Hollinden; Gary E.
Attorney, Agent or Firm: Knobbe, Martens, Olson &
Bear
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation of application Ser. No.
07/811,026, filed Dec. 19, 1991, now abandoned, which is a
continuation of application Ser. No. 07/387,947, filed Aug. 24,
1989, now U.S. Pat. No. 5,080,885, which is a continuation of
application Ser. No. 06/818,690, filed Jan. 14, 1986, now U.S. Pat.
No. 4,865,836.
Claims
I claim:
1. A fluorocarbon emulsion, prepared by:
forming a mixture consisting essentially of an aqueous phase, an
effective amount of emulsifying agent, and a fluorocarbon, said
mixture having from greater than 50% to about 125% weight per
volume of said fluorocarbon; and
passing the fluorocarbon-containing mixture through a mechanical
emulsification apparatus in which said mixture is subjected to
sufficiently high flow rams and pressures to form a stable, heat
sterilizable fluorocarbon-in-water emulsion;
wherein said emulsion is biocompatible and exhibits
substantial/particle size stability in the non-frozen state
following heat sterilization.
2. The fluorocarbon emulsion of claim 1 wherein the fluorocarbon is
a brominated fluorocarbon.
3. The fluorocarbon emulsion of claim 1 wherein the fluorocarbon is
a monobrominated perfluorocarbon.
4. The fluorocarbon emulsion of claim 1 wherein the fluorocarbon
emulsion has at least 55% weight per volume of fluorocarbon.
5. The fluorocarbon emulsion of claim 1 wherein the fluorocarbon
emulsion has at least 60% weight per volume of fluorocarbon.
6. The fluorocarbon emulsion of claim 1 wherein the fluorocarbon
emulsion has greater than 75% weight per volume of
fluorocarbon.
7. A storage stable, heat sterilizable fluorocarbon emulsion
consisting essentially of:
an continuous aqueous phase, a discontinuous fluorocarbon phase,
and an effective mount of emulsifying agent, wherein the
concentration of said fluorocarbon phase in said emulsion is
greater than 85% and no more than 125%, weight per volume, and
wherein said emulsion exhibits substantial particle size stability
on storage in the non-frozen state following heat sterilization and
is biocompatible.
8. The fluorocarbon emulsion of claim 7 wherein the fluorocarbon is
a monobrominated perfluorocarbon.
9. The fluorocarbon emulsion of claim 7 wherein the fluorocarbon is
a perfluorooctylbromide.
10. A process for preparing a fluorocarbon emulsion capable of
carrying oxygen to animal tissues, said emulsion having substantial
particle size stability characteristics for an extended period of
time and through heat sterilization, comprising the steps of:
a. forming a mixture consisting essentially of an effective mount
of an emulsifier, an aqueous phase, and from about 55% to 125%
weight per volume of a non-toxic fluorocarbon; and
b. passing the fluorocarbon-containing mixture through a mechanical
emulsifying apparatus having a flow path, in which said mixture is
subjected to sufficiently high shear rates to form a stable, heat
sterilizable emulsion.
11. A process for preparing a fluorocarbon emulsion capable of
carrying oxygen to animal tissues, said emulsion having substantial
particle size stability characteristics for an extended period of
time through heat sterilization comprising the steps of:
forming a mixture consisting essentially of an aqueous phase with
an effective amount of an emulsifier and from about 50% to about
125% weight per volume of a fluorocarbon; and
passing the fluorocarbon-containing mixture through a mechanical
emulsification apparatus in which said mixture is subjected to
sufficiently high flow rams and pressures to form a stable, heat
sterilizable emulsion.
12. The process of claim 11 wherein said fluorocarbon is
brominated.
13. The process of claim 11, wherein said fluorocarbon emulsion has
at least 60% weight per volume of fluorocarbon.
14. An emulsion according to claim 3 or claim 7 wherein the
emulsifying agent is a phospholipid.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the art of non-toxic oxygen
transport and contrast enhancement agents, and more particularly,
to stable emulsions capable of sterilization and suitable for
internal and intravenous animal (including human) use, where the
emulsion is a brominated perfluorocarbon in the discontinuous phase
in the presence of certain substances which are believed to be
stabilizing agents.
2. Description of the Prior Art
Mono-brominated cyclic and acyclic perfluorocarbons in aqueous
emulsions with a minor amount of an emulsifying agent have been
known for medical applications involving animals, including humans,
for both radiopacity and oxygen delivery. Oxygen is highly soluble
in, for example, perfluorooctylbromides. (See, Long, U.S. Pat. No.
3,818,229; No. 3,975,512; and No. 4,073,879.) The present invention
is directed toward improvements in the use of such
bromofluorocarbons wherein the oxygen transport characteristics, as
well as the storage characteristics of the emulsions are enhanced,
while the toxicity is further minimized or decreased
altogether.
In the past, efforts to use emulsified fluorocarbons as an oxygen
transport or carrier, as in a blood substitute, have encountered
certain difficulties. Purity, non-toxicity, chemical and biological
inertness and excretability are necessary objectives. The
emulsified fluorocarbon must be capable of sterilization,
preferably by heat, have long-term size and function stability in
the fluid or non-frozen state, be industrially feasible, persist
for sufficiently long times in the bloodstream when used
intravascularly and be eliminated rapidly from the body. It has
been conventionally believed that those fluorocarbons which have
fast elimination times from the body do not form stable emulsions,
and that those fluorocarbons which form stable emulsions are
retained too long in the body. Non-brominated perfluorocarbons show
a direct relationship between emulsion stability and molecular
weight and an inverse relationship between molecular weight and
excretion rates from the animal body. Both types of fluorocarbons
are inadequate, and attempts to combine amounts of both types have
merely combined the problems of each.
For intravenous use, it is considered important to have small
particle size. However, long-term storage for extended periods of
time for a month and longer, of fluorocarbon blood substitutes, or
"synthetic blood" has hereto for resulted in conglomeration of the
fluorocarbon particles of the emulsion into large particles,
specially after heat sterilization. For a general discussion of the
objectives and a review of the efforts and problems in achieving
these objectives in fluorocarbon blood substitutes, see
"Reassessment of Criteria for the Selection of Perfluoro Chemicals
for Second-Generation Blood Substitutes: Analysis of
Structure/Property Relationship" by Jean G. Riess, Artificial
Organs 8, 34-56 (1984).
Larger particle sizes are dangerous in intravenous use in that they
tend to collect in the lung, spleen and some other organs,
enlarging them and endangering their functioning. On the other
hand, it is desired to have sufficient particle size in the
fluorocarbon particles for them to collect in tumors and other
areas when the fluorocarbons are used as a contrast enhancement
medium. Larger particle sizes, also are unobjectionable when used
in other, non-venous systems in the body, such as, for example, the
cerebrospinal fluid ventricles and cavities.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In brief, one aspect of the present invention comprises
mono-brominated perfluorocarbon emulsions. The bromofluorocarbon
emulsions found suitable for use as an oxygen transport medium
comprise mono-brominated perfluorocarbons having a minor Mount of
an emulsifying agent and further comprising a compound believed to
be useful in stabilizing the membrane of the bromofluorocarbon
particle. The compound could be steroid hormones, cholesterol,
tocopherols and mixtures thereof. A nine-alpha fluorinated
corticosteroid in combination with cholesterol emulsified along
with a phosphatidylcholine to particles of a perfluorooctylbromide
having the formula CF.sub.3 (CF.sub.2).sub.6 CF.sub.2 Br or C.sub.8
F.sub.17 Br, or of related brominated perfluorocarbon such as a
perfluorohexylbromide (C.sub.6 F.sub.13 Br) or a
perfluoroseptobromide (C.sub.7 F.sub.15 Br), together with a
tocopherol as an anti-oxidant, is preferred.
It has been found that particle size stability can be maintained
with emulsions of from 20% weight per volume to 125% weight per
volume of the bromofluorocarbon without undesirable viscosity.
Herein in this specification, the expression "weight per volume" or
"w/v" will be used and understood to mean the ratio of percentage
weight per grams per 100 cubic centimeters or milliliters, or
equivalent expressions or mathematical identities thereof.
Emulsions with concentrations of from 20% to 100% weight per volume
have a thixotropic viscosity profile less than that of whole human
blood. Perfluorooctylbromide is excreted rapidly from the animal
body, because of the lipotrophic nature of the brominated
perfluorocarbon, it is believed. In any event and notwithstanding
its high molecular weight and stability, mono-brominated
perfluorocarbon has a relatively high excretion rate from the
animal body.
In some applications where high bromide concentration, such as when
the emulsion is to be used as a contrast enhancement medium, or
where a high oxygen transport is needed in an intravascular system
where large volume impact is to minimized, the larger concentration
emulsion is preferred. While it is not certain, it is considered
that these suitable and stable high bromofluorocarbon concentration
emulsions are possible because of (1) the relatively high molecular
weight of the brominated perfluorocarbon, and (2) the good bonding
between the bromine and the phospholipid emulsifying agent
discussed below.
The preferred emulsifying agent is a phospholipid, an anionic
surfactant or a fluorinated surfactant. Suitable phospholipids
include lecithin, such as phosphatidylcholine. Phospholipids are
common and biologically accepted elements in the blood, and are not
so readily phagocytosed by macrophages or other organisms in the
animal body's fluids. The resultant emulsion thus is resistent to
macrophage and other animal body organism attack.
Preferred anionic surfactants include
polyoxy-ethylenepolyoxypropylene copolymers, such as Plutonit.
Suitable fluorinated surfactants include XMO10 and XM020.
The phospholipid emulsifying agent should be included in the range
of from 2 to 14 grams weight per volume, with the preferred amount
being 6 grams weight per volume for concentrations of 75% w/v
bromofluorocarbon and 7 grams to 10 grams weight per volume for
concentrations of 100% bromofluorocarbon. The phospholipid lecithin
contains both hydrophilic and hydrophobic or lipophilic
characteristics and is thus a suitable emulsifying agent for the
perfluorocarbon particle.
According to one embodiment of the present invention, an additional
compound is made part of the particle and emulsion. The additional
component is believed to be effectual in making the discontinuous
particle membrane more compatible and stronger with respect to the
continuous, aqueous phase of the emulsion. The additional component
could be a tocopherol, asteroid hormone, a cholesterol or,
preferably, a combination of these three components. Suitable
steroid hormones include fluorinated corticosteroids, fluorinated
androgens and non-fluorinated hormones, such as progesterones and
estrogens. The preferred steroid is one that is fluorinated in
either the 9-alpha or the 6-alpha positions such as, for examples,
9-alpha-fluoro-16-alpha-methylprednisolone,
9-alpha-fluoro-16-betamethylprednisolone,
9-alpha-fluoro-16-alpha-hydroxyprednisolone and
6-alpha-fluoro-16-alpha-methylprednisolone, or combinations of
these corticosteroids.
While the actual reaction or membrane structure that takes place is
not known, it is believed that the affinity of the fluorine in the
fluorinated corticosteroid with the fluorine in the
bromofluorocarbon creates a more compatible and reliable bond
between the steroid and perfluorocarbon particle to form a more
stable membrane for the perfluorocarbon particle in the
discontinuous phase of the emulsion.
Red blood cells have cholesterol on their cell membranes removed to
be joined with the membrane of the fluorocarbon particles, which
form close union with and have an affinity for the fluorocarbon
particles, it is believed. Fluorocarbon particles having a
significant coating of the cholesterols will deter the removal of
cholesterol from the red blood cells, it is believed. Somewhat
similarly, tocopherols and steroid hormones enhance the stability
of the membrane of the perfluorocarbon particle.
The steroids 9-alpha-fluoro-16-alpha-methylprednisolone and
9-alpha-fluoro-16-beta-methylprednisolones, and other additional
components if any are combined with them, should be included in an
amount from 0.5 mg. to 5 mg. (or 0.0001 to 0.005 percent) weight
per volume (w/v) in the emulsion. Six times this quantity of the
steroid 9-alpha-fluoro-16-alpha-hydroxyprednisolone and combined
additional components may be used. Three times the range given may
be used if the steroid 6-alpha-fluoro-16-alpha-methylprednisolone
and any additional component is used. The actual amount of the
additional component or components is a function of the
contemplated dose, and of the amount of bromofluorocarbon in the
ultimate emulsion. In this specification, the term "biocompatible"
is used to denote that amount or quantity which is compatible with,
and above which toxicity results in, the biological system into
which the emulsion containing the biocompatible element is to be
introduced. There are biocompatible limits for steroids and
cholesterols. It may be that additional amounts or quantities of
the steroids and cholesterols are biocompatible, but the range
given has been found to be sufficient to achieve the particle size
stability and efficacious compatibility with red blood cells and
other components in the bloodstream and other fluid systems of the
animal body.
Other nutrients may be added to the ultimate emulsion, such as, for
example, glucose, amino acids, proteins and lipids.
Oxygen is highly soluble in the perfluorocarbons and in particular
the mono-brominated perfluorocarbons of the present invention. In
using the present invention as an oxygen transport medium, it is
important to retain the oxygen as part of the perfluorcarbon
particle for a reasonable period of time in order to transport the
oxygen throughout the vascular system or to increase intravascular
dwell time. It is found that tocopherols such as alpha-tocopherol
and water-soluble analogs of tocopherols are suitable anti-oxidants
which will retard rapid oxidation. Other anti-oxidants that are
useful are ascorbic acid and calcium ascorbate. Adding
anti-oxidants to the emulsion in an amount of from 0.01% to 0.5%
weight per volume has been found useful to retard oxidation of the
lipid emulsifier which diminishes the stability of the emulsion.
Anti-oxidants also quench free radicals such as superoxide or
hydroxyl atoms which are harmful to biological systems.
For contrast enhancement use and for oxygen transport use
internally in an animal, including humans in other than the
bloodstream, such as in the cerebrospinal system, in the eye and in
the tracheobronchial passages, for example, larger particle sizes
can be tolerated, and indeed may even be preferred. Such larger
particle sizes may provide for a more even distribution of the gas,
such as oxygen. Particle sizes of less than 400 nanometers diameter
for the substantial portion, on the order of 95% of the particles,
with a median particle diameter of less than 150 nanometers is to
be preferred, however, for use in the bloodstream. Effective oxygen
unloading or de-oxygenation occurs in the bloodstream primarily in
the capillaries, and the small bromofluorocarbon particle size is
advantageous in getting the oxygen to these capillaries. For these
sizes for use in the bloodstream, and even for the emulsions to be
used in non-vascular systems, it is highly important to maintain
particle size characteristics stable over extended periods of time,
at least more than one month and of the order of eighteen months
and more.
Perfluorocarbon emulsions in commercially usable quantities having
very small particle sizes or diameters on the order of hundreds of
nanometers using conventional particle fractionalization methods,
have been achieved according to methods disclosed herein, such as
use of homogenization techniques utilizing the Gaulin mixer.
Bromoperfluorocarbon emulsions made with such a technique appear to
be suitably stable where the concentration of the
bromoperfluorocarbon is relatively small, on the order of less than
50% weight per volume. Attempts using the Gaulin mixer to prepare
commercially usable quantities of bromoperfluorocarbon emulsions
having w/v concentrations of 50%, 75% and more and having a median
particle diameter size of less than 200 nanometers were
unsuccessful. These higher concentration bromo-perfluorocarbon
emulsions were observed to have a median particle diameter size of
more than 200 nanometers.
Long-term, extended period of time small particle size stability of
higher concentrations of mono-brominated perfluorocarbon emulsion
in an aqueous phase with a phospholipid emulsifying agent has been
found when the emulsion is formed or generated using a plural flow
impingement apparatus. The aqueous phase was buffered with sodium
monophosphate and sodium diphosphate in such an amount to give a
resultant emulsion pH of between 6.8 and 7.2. The aqueous phase,
further, was in a solution of glycerol to control the osmolarity of
the resultant emulsion for use in the bloodstream. This buffered,
aqueous phase solution in glycerol is sometimes designated the
vehicle.
The bromofluorocarbon was metered in a predetermined, measured rate
into the vehicle or aqueous phase having the emulsifying agent
mixed therein. The resulting mixture was placed into a flow path
which was divided into a plurality of flow paths. The flows were
re-directed to impinge upon each other at velocities in excess of
1500 feet per second in sheets of interaction in a cavity under
4,000 pounds per square inch or more of pressure. The resulting
bromofluorocarbon particles had a size characteristic of more than
95% smaller than 350 nanometers in diameter, with the median size
diameter of less than 150 nanometers and, significantly, these size
characteristics were maintained stable for up to sixteen months,
and even after sterilization, such as by heat or by filtration.
The present invention can be further understood by reference to the
following illustrative examples.
EXAMPLE I
Exchange transfusions were performed in female rats weighing 180 to
220 grams. The rats were anesthetized and polyethylene catheters
were inserted into the left or right jugular vein and carotid
artery. After recovery from the anesthesia, the rats were placed
into an atmosphere enriched with 50% to 60% oxygen. Blood was
removed through the carotid artery catheter and a comparable amount
of the brominated perfluorocarbon emulsion comprising 25% w/v of
perfluorooctylbromide, 4% w/v of lecithin, 0.04% w/v of
L-alpha-tocopherol, 2.21% w/v of glycerol, 0,012% w/v of sodium
diphosphate, 0.057% w/v of sodium monophosphate, and the aqueous
phase. The transfusion was continued until the red blood cell count
of the rat was reduced to 50% of the baseline value. The rats were
kept in the oxygen enriched atmosphere for twenty-four hours, after
which they were removed to the ordinary atmosphere. All rats
survived for more than one month.
EXAMPLE II
The experiment of Example I was repeated, except that the
brominated perfluorocarbon emulsion comprised 50% w/v of
perfluorooctylbromide. All other parameters were the same. All rats
survived for more than one month.
EXAMPLE III
BALB/c Mice were administered intravenously the brominated
perfluorocarbon emulsion at doses of 45 grams per kilogram of body
weight, and were administered intraperitoneally the brominated
perfluorocarbon emulsion in doses of 100 grams per kilogram of body
weight. The emulsion comprised 100% w/v of perfluorooctylbromide,
9.1% w/v of lecithin, 0.2% w/v of
6-alpha-fluoro-16-alpha-methylprednisolone, 0.2% w/v of
alpha-tocopherol, 1.0% w/v of glycerol, 0,012% w/v of sodium
diphosphate, 0.057% w/v of sodium monophosphate, and the aqueous
phase. After seven days the liver and spleen were enlarged, but the
peritoneal cavity showed no signs of inflammation, and the lungs
were normal and filled with oxygen. There were no signs of
hemorrhage or pulmonary congestion, or of inflammation of the
tissues of the abdominal wall.
EXAMPLE IV
A mono-brominated perfluorocarbon emulsion comprising 100% w/v of
perfluorooctylbromide, 9.1% w/v of lecithin, 0.02% w/v of
6-alpha-fluoro-16-alpha-methylprednisolone, 0.2% w/v of
alpha-tocopherol, 1.0% w/v of glycerol, 0.012% w/v of sodium
diphosphate, 0.057% w/v of sodium monophosphate, and the aqueous
phase, was prepared by first preparing the vehicle of the
continuous or aqueous phase by blending in the lecithin, the
6-alpha-fluoro-16-alpha-methylprednisolone, the alpha-tocopherol,
the glycerol, the sodium diphosphate, and the sodium monophosphate.
The perfluorooctylbromide was added in a measured rate into the
vehicle while mixing. The resulting emulsion at 10.degree. C. was
passed through a microfluidizing apparatus in the method described
herein where a plurality of flows of the emulsion were impinged
upon each other at velocities in excess of 1500 feet per second,
for 15 passes.
The particle size distribution was analyzed in a Nicomp sub-micron
particle sizer manufactured by Pacific Scientific Company of
Anaheim, Calif. This analyzer determines relative quantities of
various sized particles by a method of dynamic light scattering.
Results indicated that the majority of particles ranged in diameter
from about 84.2 to 87.2 nanometers, and a significantly smaller
population of particles had a diameter ranging from about 200.0 to
252.6 nanometers.
The emulsion was then sterilized at 90.degree. C. for fifteen
minutes. After sterilization, the Nicomp emulsion particle sizer
characteristics were measured on the Nicomp particle sizer. The
results of this analysis showed no significant particle size
characteristic deterioration or change from that noted above; the
majority of particles again ranged in diameter from about 84.2 to
87.2 nanometers, and a significantly smaller population of
particles had a diameter ranging from about 208.6 to 266.6
nanometers.
EXAMPLE V
The emulsion particle size stability over an extended period of
time was studied by analyzing the particle size distribution in a
Nicomp sub-micron particle sizer identified above in Example IV.
The brominated perfluorocarbon emulsion first was made by the
methods described above and comprised 25% w/v of
perfluorooctylbromide, 4% w/v of lecithin, 0.04% w/v of
L-alpha-tocopherol, 2.21% w/v of glycerol, 0.012% w/v of sodium
diphosphate, 0.057% w/v of sodium monophosphate, and the aqueous
phase. The emulsion was analyzed shortly after formulation, and the
relative quantities of the emulsion's particle sizes is as follows:
results indicated that the majority of particles ranged in diameter
from about 76.5 to 85.7 nanometers, and a significantly smaller
population of particles had a diameter ranging from about 240.0 to
359.9 nanometers.
The emulsion was stored at 4.degree. C., although, due to various
interruptions during the time of storage, the temperature was
changed, and was frequently much higher than 4.degree. C. A second
and substantially identical analysis was made using the Nicomp
particle sizer as described above, some fifteen months and
twenty-two days after the analysis given immediately above. The
results of the second analysis indicated that the majority of
particles ranged in diameter from about 24.0 to 26.6 nanometers,
and two extremely minor populations of particles having a diameter
ranging from about 85.7 to 133.3 nanometers and about 200.0 to
1200.0 nanometers were also detected.
The foregoing detailed description of the invention and of the
preferred embodiments, as to products, compositions and processes,
is illustrative of specific embodiments only. It is to be
understood, however, that additional embodiments may be perceived
by those skilled in the art. The embodiments described herein,
together with said additional embodiments, are considered to be
within the scope of the present invention.
* * * * *